Distributing system for electric railways.



'A W. COPLEY & C. LE G. .FORTESCUE.

DISTRIBUTING SYSTEM FOR ELECTRIC RAILWAYS.

APPLICATION FILED DEC. 14, 1915.

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I I l WITNESSES?- 25 INVENTOR F/KZ 4/ W5 Z206. M 7 mfiggzgai r I or escue l I ATTORNEY UNITED STATES PATENT orricn.

ALMON 'W. COPLEY, OF WILKINSBURG, AND CHARLES LE G. FORTESCUE, OF PITTS- BURGH, PENNSYLVANIA, ASSIGNORS TO WESTINGHOUSE ELECTRIC AND MANU- FACTURING COMPANY, CORPORATION OF PENNSYLVANIA.

DISTRIBUTING SYSTEM FOR ELECTRIC RAILWAYS.

' Specification of Letters Patent.

Patented Mar. 4.1919.

Application iled December 14, 1915. Serial m). 66,733.

To all whom it may concern:

Be it known that we, ALMoN W. Corner, a citizen of the United States, and a resident of Wilkinsburg, in the county of Allegheny '5 and State of Pennsylvania, and CHARLES Ln G. Fon'rnsoun, a subject of the King of Great Britain, and a resident of Pittsburgh,

in the county of Allegheny and State of Pennsylvania, have invented a new and use-' ful Improvement in Distributing Systems for Electric Railways, of which the following is a specification.

Our invention relates to electrical distributing systems and particularly to electric railway systems that employ alternating currents for propulsion purposes.

More particularly, our invention relates to electric railway systems of the above-indicated character which embody means for minimizing inductive disturbances that arise from the flow of propulsion currents and are so impressed upon adjacent circuits as to interfere with the satisfactory operation of the latter. I

Intelligence-transmission circuits, such as telephone and telegraph circuits, are fre quently disposed adjacent to electric railways and are, therefore, subject to inductive disturbances arising from the flow of the propulsion currents in the railway circuit. Ordinarily, the inductive disturbances occasioned by the flow of power currents are given free play because the return currents flowing through the earth and the track rails are so remotely removed from the trolley currents that the inductive effects arising from the currents flowing in the trolley and the rails do not neutralize each other to any appreciable extent. Many systems have been proposed for minimizing the inductive disturbances impressed upon adjacent intelligence-transmission circuits, but

I complete neutralization of the inductive effects has not been obtained in all cases. A particular system which has given fairly good results embodies the use of series transformers to inductively interlink the trolley conductor and the track circuit, whereby the return flow of the trolley currents may be confined to the track rails or to portions of the earth which are closely adjacent to the track rails. In this manner, the zones of disturbing inductive influences arising from 29, 1916, on an application filed by Charles F. Scott. 7

In our present system, we contemplate the use of series transformers forinterlinking the trolley conductor with a feeder conductor and also provide means whereby the propulsion currents may be confined to limited sections of the track circuit. It is intended that the feeder conductor and the trolley conductor shall be so positioned with respect to the adjacent intelligence-transmission circuit, which it is desired to pro-. tect against inductive disturbances, that the electromotive forces induced therein by reason of the trolley and feeder currents, shall be substantially neutralized. Under the most favorable conditions of operation, the resultant electromotive forces induced in the adjacent transmission circuit will be zero because of the neutralization of the inductive efl'ects generated by the outgoing and the return flow of the propulsion currents.

One object of our invention is to provide a distributing system for alternating currents in which disturbances arising therefrom that tend to interfere with the satisfactory operation of other circuits adjacent thereto, such as intelligence-transmission circuits, may be completely neutralized in orintelligenceover the circuits subject to such disturbances. r i f .For a better understanding of the nature and scope of our invention, reference may be had to the following description and the accompanying drawing in which Figure 1 is a dia amrnatic view of a railwaysystem embo ying one form of our invention, and Fig. 2 is a simplified diagram illustrating the system of Fi 1. Referring to %ig. 1, a trolley conductor 1 supplies power to a railway system c0mpr1s- 105 ing a track circuit 2 that is divided into a der to insure satisfactory transmission of plurality of insulated block sections 3 for signaling purposes. A return feeder l paralleling the trolley conductor 1 provides means whereby the propulsion currents may return to a source of power supply, represented as a single-phase alternator 5. One terminal of the alternator 5 is connected to the trolley conductor 1 and the other terminal is connected to the return feeder a, the full potential of the alternator 5 being impressed across the aforementioned conductors. At spaced intervals in the trolley conductor 1, are insulating joints 6,SlI11llA-l' joints 6 being positioned at corresponding points in the return feeder 41-. F or convenience, the insulating joints 6 may be placed at points corresponding to the position of insulating joints 7 in the track circuit 2, the latter bein provided in order that sections of the tram circuit may be employed as local circuits for the electric signalin system. On both sides of the insulating oints 6 and 6 are disposed transformers 8 and 9 and 8 and 9, respectively. The primary windings 10 and 10 of the transformers 8 and 9 are connected in series-circuit relationship with the trolley conductor 1 and in shunt to the insulating joint 6, and the secondary windof the trolley and feeder conductors 1 and 4 are two transformers 12 and 13, one having a winding 14 and a winding 15, and the other having a winding 14* and a winding 15*. The windings of each of said transformers are connected to each other at a common point 16. The common points 16 of the transformers are connected to each other through conductors 17 and 1'? and windings 18 and 18 ,the latter embracing the transformer core members-of the transformers 8 and 9. An intermediate connector 19 between the two coils 18 and 18 is connected through a conductor 20 to mid-points 2-1 on impedance bonds 22 that are inserted on both sides of the track insulating joints '7.

The impedance bonds 22 are. of the usual form of construction and are usually employed when an electric signaling system, comprising insulated block sections, is associated with the railway circuit. This method of applying impedance bonds is old in the artand the form of construction of such devices is Well known.

The free terminals of the windings 15 and 15 of the transformers 12 and 13 are conon nected to a common conductor 23 which, in

messes turn, is connected to a series connector 24 extending between the windings 10 and 10 of the transformers 8 and 9, and similarly,

the free terminals of the windings 1-1 and.

14 are connected to a common conductor 25 which, in turn, is connected through a conductor 26 to a series connector 26 that extends between the coils 11 and 11 of the transformers 8 and 9.

From the foregoing, it will be apparent that the trolley conductor 1 is continuous because the coils 10 and 10 of the transformers 8 and 9 are connected in series-circuit relationship with each other and in shunt to the insulating joint 6, and the return feeder 4 is likewise continuous because the series connected coils 11 and 11 of the transformers 8 and 9 are connected in shunt to the insulating joint 6*. Again, the windings 14 and 15 and the windings 14 and 15 of the transformers 12 and 13, respectively, are connected between the trolley conductor and the.

return feeder, their intermediate points 16 being connected through the coils 18 of the transformers 8 and 9 to the track circuit 2. The transformers 8 and 9 inductively interlink the track circuit 2 with the trolley conductor 1 and the return feeder 4E. Referring to the signaling system, each block section 6 constitutes a local circuit which is connected to a signaling circuit 27 by means of track transformers 28. A signaling relay 29 is subject to the inductive influences of a winding 30 that isconnected I across the rails of the track sections 3, and

to a winding 31 that is energized through i a second track transformer 32 and serves to control a local circuit 33 by means of which a. signaling device 34 'is actuated. Inasmuch as this signaling system is old in the art, further explanation thereof is not deemed necessary.'

An intelligence-transmission circuit 35, shown as a telephone circuit, is disposed" in proximity to the trolley conductor 1 and the feeder and is, therefor-3, subject to the inductive effects arising from the flow. of

propulsion currents in the railway system.

For the satisfactory operation of the telephone circuit 35, itxis essential that the inductive disturbances impressed thereupon be minimized and, to this end, our distributing system substantially recludes the flow of induced currents that may arise from the flow of the propulsion currents in the railway system, as will be hereinafter disclosed.

It will be observed in connection with the above described railway system that the system is one of those known as a double-potential system, that is, twice the voltage exists between the trolley conductor and the feeder circuit that exists between either the" trolley conductor and the track circuit, or the feeder circuit and the track circuit, separately. By

the use of such a system, it is possible to obtain approximately double the efficiency of transmission which may be obtained in asingle-potential system.

However, in order to employ such a system in connection with means for minimizing the inductive interference which is frequently met with when such systems are placed in proximity to intelligence-transmission conductors, it is necessary to separate such a system into sections by so associating sectionalizing transformers with these circuits that all of the Working current used by a vehicle in any one section will flow in that track section only.

Only by so the flow of track currents to specific sections is it possible to subsequently reduce the algebraic sum of the ampere turns of the three associated circuits to zero.

Since this last reduction to zero is the essential feature of a system constructed in accordance'with my invention, it is obvious that, at thesame time,'I desire to employ sectionalized railway systems as has been hereinbefore set forth.

It is well known that the electromotive' forces induced in a disturbed. circuit are proportional to the current flow over the disturbing circuit, the extent of the disturbing zones and the proximity of the circuits to one another. Therefore, by properly proportioning the current flow in the several directions in the disturbing circuit and by suitably placing the'circuit conductors with respect to the telephone circuit, the electromotive forces induced in the telephone-circuit may be substantially neutralized inducing therein equal and oppositely directed electromotive forces, under all conditions of load distribution on the railway system.

In Fig. 2, we have shown a simplified form of the system shown in Fig. 1 the inductive windings .of the transformers having the same designations as in Fig. 1 but being more suitably arranged to facilitate explaining their inter-relations. The signaling system, for simplicity, has been dispensed with and,'as'a result, the track circuit 2 is devoid of the impedance bonds 22 of Fig. 1, the track circuit, in this instance, being considered as continuous and comprising two rails. ,Again, for the purpose of illustration only, assume that the telephone circuit 35 is uniformly spaced throughout its length from the trolley conductor 1 and the return feeder 1. The track circuit 2, in this instance, is held at a potential midway between those of the trolley conductor 1 and the feeder conductor 4; .by means of the transformers 12 and 13 which are {connected to the track circuit through theiwindings 18 and 18 of the series transforniers 8 and 9. Accordingly, the ratios of the, windings of the transformers 12 and 13 are unity, the secondary windings 14 and 14 having insectionalizing and confiningv flows along the track circuit 2,

duced therein electromotive forces equal to those impressed upon the windings 15 and 15", since the windings 14 and 15 and the windings 1& and 15 are inductively related. Furthermore, the windings 10, 11 and 18 and the windings 11 and 18* are inductively related to one another and comprise equal numbers of turns.

To further illustrate the electric conditions obtaining in the railway system of Fig. 2 at a certain instant, assume that a locomotive or train 36 occupies a mid-position on a track section intermediate the two groups of transformers. The propulsion currents, which traverse the main trolley and feeder circuits and the direction of flow of which is represented by the full line arrows 37, flow through the windings 10 and 10 of the transformers 8 and 9 along the trolley conductor 1, a trolley pole 38 and a train 36. At this point, the propulsion current divides equally in two portions that flow along the track circuit 2 in opposite directions, since it is presumedthat the track circuit 2 constitutes a uniform conductor, that the train 36 occupies a mid-position thereupon, as mentioned above, impedance of the feeder section 4 is negligible. ()ne-half of the propulsion current flows through the rail bond 20*, the winding 18 of the transformer 9, a connector 17*, the primary winding of the transformer 13, the conductors 26 and 26- and the winding 11 of the transformer 8 to the return feeder 4. The other half of the propulsion current the rail bond the winding 18 of the transformer 8, a connector 17, the primary winding 15 of the transformer 12, the conductors 26 and 26 and a Winding 11 of the transformer 8*, to the return feeder 4- half of the propulsion current flows in the path of the first half.

It will be apparent, therefore, that the propulsion current flowing in the trolley section intermediate the generator 5 and the point A of the system is equal in value, and flows in a direction opposite to, that of the propulsion current flowing in a corresponding portion of the return feeder 4. Therefore, the inductive effects arising from the flow of the propulsion current over this portion of the system are neutralized.

It becomes-'.necessary. therefore. to neutralize the inductive effects arising from the How of the propulsion current in the por tion of the railway system extending between the two' groups'of transformers.

As mentioned above, one-half of the propulsion current flows through the winding 15 of the transformer 13. An equal and oppositely directed current is. therefore, induced in the winding 14* of the transformer 13 which is represented, in direction, by the broken line arrows 38. A local circuit is and that the where the second i V consequently established over which an induced current equal one-half of the propulsion current flows, and this local circuit comprises the winding 14: of the transformer 13, thewinding 10" of the trans. former 9, a section of the trolley conductor quence thereof, a current, represented by the dot and. dash arrows 39, that is equal to the second portion of the propulsion current is induced in a second local circuit which comprises a winding 14 of the transformer 12, a conductor 23, a winding 10 of the transformer 8 a section of the trolley conductor 1, the trolley ole 38, the train 36, a section of the rai circuit 2, a track bond 20 and the winding 18* of the transformer 8 Since the induced current flowing through the winding 14* is equal and opposite to the induced current flowing in the winding 14, the separate inductive efiects impressed upon the telephone conductor 35 by the said currents of the aforementioned local circuits,

traversing the trolley conductor l are neutralized. Again, the inductive efi'ects arising from the propulsion current flowing along the trolley conductor l from the point A to the trolley pole 38* are neutralized by the inductive efiects arising from the return flow of the portions of the propulsion currents that flow along the section 4 of the return feeder that is intermediate the two groups of transformers. This may be explained in the following manner. As previously presumed, the train 38'occupies a mid position on the track section 3. The section of thetrolley conductor 1 between the point A and they-trolley pole 38* over which the propulsion current flows subtends a length of the'lt'elephone circuit 35 equal to one-half the length of the telephone circuit subtended by the'a-forementioned corresponding return feeder section 4. Therefore, the inductiveefiects arising-from the propulsion current are neutralized.

As a result of the aforementioned distribution of the propulsion currents, the 111- dnc'tive disturbances impressed upon the telephone circuits 35 are nil, since the induced electromotive forces are completely neutralized.

When the track circuit 2 is held at midpotential, the windings of the transformers 12, 13, 12 and 13" possess the same impedance, and, therefore, it may be desirable to dispose the windings 14, 15, 14 =and, 15 on the same magnetizable' core member in order to conserve space and permit of more such uniform construction that the propulmay be substantiallyneutralized. It will flowing in the several local circuits estabthe potential of said return feeder, and ineconomical structures. This can be mathematically demonstrated and, under certain conditions of operation, may be the preferred form. The transformers 8, 9, 8 and 9 interlink the trolley conductor 1, the track cir- 7 'cuit 2 and the return feeder 4 to one another, and, by their employment, the algebraic sum of the ampere turns of the windings of said transformers is, at all times, made equal to zero. 7 It is understood that the several transformers constituting each class-are to be so designed that the propulsion currents may so divide as to be inversely proportional to the impedances of the several local circuits 8 that are established by the locomotive when it occupies a position upon the railway system between-the transformer groups. Under these circumstances, the induced electromotive forces impressed upon the tele- 8; phone circuit 35 will be substantially neutralized. While, in practice, the impedances of corresponding elements comprising these several local circuits may not be exactly equal, it is possible to supply apparatus of 94 sion current will divide in accordance with the position occupied by the locomotive on the system, as explained above, thus insuring that negligible disturbances only will be 9 impressed upon the telephone circuit 35.

In a. modification of our system, the ratio between the transformer windings of the transformers 12, 13, 12 and 13 need not necessarily be unity, as .wehave assumed in the foregoing description. The potential of the track circuit 2 may have a different value than that of the mid-potential between the trolley conductor 1 and the return feeder 4,. In this instance, however, the spacin of the trolley conductor 1 and the return. eeder 4 with respect to the telephone circuit 35 should be so adjusted and proportioned that the inductive effects impressed thereupon by reason of the flow of the propulsion currents be presumed, however, that the currents lished by, and comprising the locomotive, will be inversely proportional to the impedances of said circuits.

While we have shown and described in detail one embodiment of our invention, it will be understood by those skilled in the art that many modifications thereof may be made therein without departing from the spirit and scope of the appended claims.

o claim as our invention:

1. An electric railway system comprisin a trolley conductor, a return feeder, a trac i circuit held at a potential mid-way between the potential of said trolley conductor and ductively related windings for interlinkin the trolley circuit, track circuit and returi feeder in such manner that the algebraic sum of the ampere turns of said inductively related windings is, at all times, equal to zero.

2. An electric railway system comprising 5 a trolley conductor, a return feeder therefor,

a track circuit held. at a potential midway between the potential of said trolley conductor and the potential of said feeder circuit, and inductively related windings connected in series relationship therewith for interlinking saidconductors to one another in such manner that the algebraic sum of the ampere turns of said inductively related windings is, at all times, equal to zero.

3. An electric railway a trolley conductor, a return feeder therefor, a track circuit held at a potential mid-way between the potential of said trolley conductor and the potential of said feeder circuit, a transformer having its inducing and induced windings connected in series relationship between the trolley conductor and the feeder, whereby saidrailway system is sectionalized, and inductively related windings for interlinking the trolley conductor, the feeder and the track circuit to one another in such manner that the algebraic sum of the ampere turns of said inductively related windings is, at all times, equal to zero, one of said inductively related windings connecting said transformer-windings to the track circuit.

4:. An electric railway system comprising a trolley conductor, a return feeder therefor, a track circuit held at a potential mid-way between the potential of said trolley conductor and the potential of said return feeder, inductively related windings to interlink them to one another, and a transformer having its primary winding connected through one of said inductively related windings to the track circuit and through another of said inductively related windings to the return feeder, and its secondary winding likewise connected to the track circuit and the trolley conductor.

5. An electric railway system comprising a trolley conductor, a return feeder therefor, a track circuit, a source of current supply connected to the trolley and feeder conductors, means for charging the track circuit to a potential intermediate those of the trolley return feeder, transformer windings for interlinking the track, the trolley conductor and the return feeder in such manner that the algebraic sum of the ampere turns of said system comprising transformer windings is, at all times, equal to zero, and a transformer having its pri mary winding connected between the track and the return feeder and its secondary winding connected between the track and the' trolley conductor, whereby said track circuit is held at a potential mid-way between the potential of said trolley conductor and the potential of said return feeder.

7. A railway system comprising a track circuit, a trolley conductor, a return feeder therefor, a source of current supply having its'terminals connected to the trolley conductor and the return feeder, inductively related windings inserted in circuit with the trolley and feeder conductors for inductively interlinking. them to each other, a transformer having a terminal of one winding connected to the feeder and a terminal of another winding connected to the trolley, and a third inductive winding for connecting the free terminals of said transformer windings to the track circuit, said third Winding inductively interlinking the track with the trolley and feeder conductors, whereby said track circuit is held at a potential midway between the potential of said trolley conductor and the potential of said return feeder.

8. An electric railway system comprising a trolley conductor, a return feeder therefor, a track circuit, inductively related windings placed at correspondingly spaced intervals in said conductors to interlink them to one another, and transformers correspondingly placed and having inductively related windings connected across the trolley conductor and the track circuit and across the return .placed at correspondingly spaced intervals .in said conductors to interlink them to one another, and transformers having their windings connected to said conductors through said inductively related windings,

the primary windings of the transformers being connected between the return feeder and the track circuit, and the secondary windings being connected between the track circuit and the trolley conductor to sectionalize said system and to hold the potential of said track circuit mid-way between the potential of said trolley conductor and the potential of said feeder circuit.

10. An electric railway system comprising a trolley conductor, a return feeder therefor, a track circuit, inductively related windings placed at correspondingly spaced intervals in said conductors to interlink them to one another in such manner that the algebraic sum of the ampere turns of said windings is, at all times, equal to zero, and other inductively related windings connected across the trolley conductor and the rail circuit and the feeder and the rail circuit through said first inductively related winding, whereby induced currents are caused to flow in two local circuits comprising the load point, the rail circuit, the said windings connected between the trolley conductor and the rail circuit and the trolley conductor.

11. An electric railway system comprising a trolley conductor, .a return feeder therefor, a track circuit held at a potential mid-way between the potential of said trolley conductor and the potential of said feeder, insulating joints inserted at corresponding points in the trolley conductor, feeder conductor and track circuit, inductively related windings on both sides of said insulating joints to interlink the trolley and feeder conductors, primary and secondary transformer windings connected in series relationship thereacross, and other inductive windings connected to the rail circuit at corresponding points for connecting thereto said transformerwindings, said last windings being inductively related to said windings (1151 posed on both sides of the insulating jointsin the trolley and feeder conductors.

1 12. An electric railway system comprising a trolley conductor, a return feeder therefor, a track circuit, insulating joints inserted at corresponding points in the trolley and feeder conductors, inductively related Win ings having the same number of turns connected in series circuit on both sides of said insulating joints to interlink the trolley and feeder conductors, primary and secondary windings of other transformersha ing unity ratio which are connected in series relationship thereacross, and other windings having the same number of turns as the aforementioned windings connected in series circuit with the trolley and feeder conductors being connected to the rail circuit at corresponding points so as to'connect thereto said transformer windings which are connected across the trolley and feeder conductors.

In testimony whereof, we have hereunto subscribed our names this 8th day of Dec, 

